Global Challenges Podcast - American Chemical Society



Global Challenges/Chemistry Solutions

Confronting Climate Change – Part 1

Stopgap measures to reduce greenhouse gas emissions

Combating disease … providing clean water and safe food … developing new sources of energy … confronting climate change. Hello from Washington, D.C. This is “Global Challenges” – a special podcast from the American Chemical Society, whose 160,000 members make up the world’s largest scientific society. In every period of history, the world has faced perplexing problems and daunting difficulties. Today’s headlines are a drumbeat of dilemmas that affect the everyday lives of people everywhere. “Global Challenges” takes you behind those headlines for eye-opening glimpses of how chemistry is responding to those challenges – improving and sometimes saving people’s lives. You’ll hear the stories and meet the scientists whose discoveries are helping to make life longer, healthier, and happier for millions of people. Today’s global challenge in the ongoing saga of chemistry for life: Confronting global climate change by reducing emissions of greenhouse gases.

In the late 1700s and 1800s, wagon trains of pioneers headed West to settle the American frontier. They encountered oceans of grass swaying in the wind in the prairies. Erase any mental image of Kentucky bluegrass growing a few inches high in a carefully manicured suburban lawn.

The pioneers found grass that grew 7-10 feet high — almost to the second story windows on a modern house. This grass was so tall and thick that cattle got lost in its midst, as if in an impenetrable forest. Men had to stand on the back of a horse to find the lost steers. The monster grasses were part of a vast ecosystem that covered millions of acres of the United States up to the eastern approach to the Rocky Mountains.

Much of that green ocean consisted of switch grass. Today switchgrass is looking greener than ever to new generations of pioneers. Those pioneers are chemists, chemical engineers, and other scientists who are searching for solutions to the challenges of global warming.

There is very little doubt among the great majority of scientists that observed climate trends are due to human activities. These anthropogenic threats are serious and action is urgently needed to mitigate the risks of climate change. The vast weight of scientific evidence indicates that warming trends over the next 50 years will have profound affects, not only on climate but on food supply, on our current ecosystem, and on world socio-political structures. Without rapid action to reduce the impact of excessive greenhouse gas emissions, humanity needs to fear that the effects of climate change may become irreversible.

The United States Congress got that stark assessment of global warming’s potential impact in June 2008. The speaker: Dr. Bruce E. Bursten, president of the American Chemical Society and dean of the College of Arts and Sciences at the University of Tennessee, Knoxville. The ACS, like other scientific groups, has warned of “potentially disastrous” consequences from climate change — including floods, heat waves, and droughts. So, how did we get into such a predicament? Bluntly put, we did it ourselves. Most research concludes that global warming probably is anthropogenic — caused by humans, not Mother Nature.

Over the past 150 years or so, as the world has become more industrialized, mobile, and heavily populated. Fossil fuels have fed that growth. And burning these fuels — especially coal, oil, and natural gas — fosters the process behind global warming, which is known as the “greenhouse effect.” Intensive agriculture to sustain population growth is another major contributor to the greenhouse effect.

Greenhouse Earth

The greenhouse effect results from a build-up of gases — such as carbon dioxide and methane — in Earth’s atmosphere. CO2 comes from burning. Burning coal in electric power generating plants. Burning gasoline in car engines. Burning trees in rainforests to clear land for farming, and from other sources.

Much of the methane, which is 21 times more potent as a greenhouse gas than carbon dioxide, comes from raising cattle, and growing rice in flooded fields. Cattle release methane from their bodies, and in their manure. Swamps also generate methane in a natural process. Those gases accumulate in Earth’s atmosphere and act much like the panes of glass in a greenhouse.

Sunlight passes right through and heats thing up. But heat gets trapped and cannot escape back into space. Scientists are seeking solutions, ways to stop and even reverse the rapidly rising levels of carbon dioxide.

Atmospheric levels of carbon dioxide reached nearly 385 parts per million in 2007, up from 280 in 1850 and an increase of 2.6 parts per million from 2006. And we need new ways of raising cattle and growing rice — staple food for one-third of the world’s population — that minimize releases of methane. You will hear about some of those longer-term solutions in Part Two of this podcast. Scientists also are working on stop-gap measures that can be put into effect in the short term.

What’s important to remember about climate change, in solving it, is that we’re not going to get there tomorrow. We’re starting basically at business as usual. For all the talk, you know, we haven’t changed anything in the last 20 years.

That’s Dr. Frank S. Zeman, of Columbia University, an expert who reported on responses to global warming in March in Environmental Science & Technology, one of the American Chemical Society’s 36 peer-reviewed scientific journals. Some of those solutions include more energy-efficient buildings, greener industrial processes; alternative energy sources; improved fuel-efficient vehicles; and urban planning that encourages mass transit.

Capturing Carbon Dioxide

One of the most promising ways of reducing releases of carbon dioxide is to capture and sequester, or store, the gas — lock the gas away so it can’t get out again. Proposals for CO2 sequestration include collecting the gas and pumping it down into spent oil or natural gas wells, storing it in the deep ocean as an icy material, and reacting CO2 with metal oxides to produce stable carbonates. Power plant smoke stacks in the United States alone release almost 2.5 trillion tons of CO2 annually. Researchers are looking at several new technologies to capture and eliminate some of that enormous volume of gas in an economical fashion. Dianne Wiley, a chemical engineer with Australia’s University of New South Wales and the Australian Cooperative Center for Greenhouse Gas Technologies, is one of those researchers.

I guess the thing to understand with all of these technologies is that those costs are quite high, particularly if you compare to the European Union estimate for carbon trading, we should be looking around about the $30 per ton to enable this to be an implementable technology.

Some current CO2 capture technologies typically cost about $50 to $60 per ton. In a report published in June 2008 in the ACS journal, Industrial and Engineering Chemistry Research, Wiley examined some adsorption technologies and explained what’s needed to bring costs down to about $30 per ton.

According to our calculations, we would need the scientists who are  developing the adsorbents to probably at least double the capacity at which carbon dioxide can be adsorbed and almost triple the selectivity. This would reduce the weight and costs of the adsorbents needed significantly. For example, if you want to capture 3 million tons of CO2 from a typical power plant, if you’re using current commercial products you’d need something around about 500 tons of adsorbent and that would cost approximately $6 million. By developing better adsorbents, we’d hope that we’d be able to halve the costs. So the capture costs would go down from about $60 a ton to about $30 a ton.

A Fondness for Fossil Fuels

Despite worldwide concern about CO2 emissions, and research on alternative fuels, the U.S. Department of Energy says dependence on oil, coal, and other fossil fuels may actually increase between now and the 2020s. In an address at ACS’s 2008 National Meeting in New Orleans, Dr. Raymond Orbach, the energy department’s undersecretary for science, said that it will be difficult to move away from those fuels.

Orbach described the energy quandary in the 21st Century as one of the biggest challenges humanity has ever faced. Two of the most important questions, according to Orbach, are: How will we supply all the needed new energy? And how can we do it without adding greenhouse gases to the atmosphere?

Meeting that challenge, Orbach said, will demand “transformational breakthroughs in basic science.” He meant once-in-a-lifetime revolutionary discoveries, rather than the one-small-step-advances that happen all the time in science.

“Bridge” Fuels & “Stranded” Gas

So, what’s to be done in the meantime while scientists are tackling that challenge? One stop-gap measure to reduce CO2 emissions involves the use of so-called “bridge fuels.” Here is Dr. Zeman:

A bridge fuel is, as the name implies, something to get us from here to there; here being our current system, which is gasoline derived from oil or diesel derived from oil, to there, which would be something I guess you could call the hydrogen economy, something akin to the hydrogen economy … you know, where we have a fuel that we can use that does not affect the climate. So, a carbon-neutral fuel or fuel that doesn’t have carbon.

Global Challenges asked Dr. Zeman about an idea for using so-called “stranded” natural gas. Natural gas of this kind may be located in fields so far away from markets that building pipelines would be uneconomical. The gas is marooned, left high and dry and unusable.

We were proposing to use stranded gas as the main feedstock. Now, we know natural gas is a sort of climate-friendly fuel compared to coal in the sense that the energy released per unit, carbon dioxide is twice that of coal. So, if you want to look at it that way, it’s twice as good for the climate as coal is. But not all of it can make it to market because some of it is just left somewhere where there’s no pipeline and there’s no infrastructure or it’s too expensive to build the infrastructure to get this fuel to market. So what we thought was rather than bring the fuel to market, why don’t we bring the market to the fuel? And in some ways, instead of a pipeline network like the trans-Canadian or the Alberta … the Alaskan pipeline, you have this modular or movable plant that can go up to the fuel, make liquid carbon … like make liquid fuels, which then you can transport back away from it. The process is based on combining this stranded gas with carbon dioxide. So, there you can see how it’s a bridge fuel because we’re taking a waste product and turning it back into a fuel.

Saudi Arabia of Coal

With crude oil prices at record levels, coal is getting more and more attention as a more economical alternative with abundant domestic supplies. The United States is the Saudi Arabia of coal. U. S. coal reserves total almost 270 billion tons — 27 percent of the world total. Saudi Arabia has about 20 percent of the world’s oil reserves.

Coal-fired electric power plants long have produced almost 50 percent of the electricity consumed in the United States. Coal, however, is the single largest source of carbon dioxide released into the atmosphere.

Switching to Switchgrass

Is there any way to increase use of coal, while minimizing releases of that greenhouse gas? The answer takes us back to those pioneers and seas of switch grass that launched this episode of Global Challenges. Dr. William Morrow, a senior consultant with Energy & Environmental Economics Inc. in San Francisco, believes there’s a way to reduce CO2 emissions while still using coal to fire our power plants. In April 2008, Morrow reported in the ACS journal, Environmental Science & Technology, that mixing switchgrass with coal can help reduce carbon dioxide emissions.

Let’s say that you’re putting a ton of switchgrass into an existing coal-fired power plant, you will displace roughly a half a ton of coal when you do so. And a ton of coal will produce a certain amount of CO2, depending on the carbon content of the coal. So, displacing a half a ton of that coal will displace half of the CO2 that would have been emitted from that ton of coal.

Morrow tackled the research to check on the impact — the CO2 reduction — of using switch grass in the generation of electricity rather than in producing ethanol for cars. He found that roughly 2-3 times the amount of CO2 could be displaced if switchgrass is used to displace coal, rather than using it for ethanol production.

Our estimate is roughly between 200 to 350, 325 million English short tons per year … that’s about 16 ... excuse me … 10 to 16 percent of the CO2 that is emitted in the electricity sector within the United States.

If all of the switchgrass that is forecasted to be capable of being grown were to go into the electricity sector. This quantity of switchgrass has the capability, depending on what future technologies are going to be, of producing maybe about 26 to 40 billion gallons of ethanol per year, which we’re currently consuming 140, 150 billion gallons of gasoline per year. So, it depends on the values that the United States as a public wants to go for in the future. Do we want to have alternative transportation fuels or do we want to mitigate CO2? You mitigate more CO2 by using this switchgrass in the electricity sector than you would if you used it in the transportation sector.

Switchgrass is just one of the many so-called biofuels – corn and other organic matter that comes from renewable plants, trees, crops, and waste materials. Future episodes of Global Challenges will focus on biofuels, and differing views on their potential.

For the average person though, controlling climate change by using switchgrass or capturing and storing carbon dioxide are things that only scientists and engineers really understand and can accomplish. Some people might very well ask, so what can I do about climate change?

As it turns out, more than you might think. You’ve probably heard most of these suggestions for reducing your personal carbon dioxide footprint:

• Carpool, take public transportation, or maybe even walk or ride a bicycle;

• Turn off the lights and TV when you leave a room;

• Turn down the heat and raise the a/c setting on your thermostat;

• Recycle;

• Replace old appliances with ones that are more energy efficient.

Science to Chew On

The latest research is giving consumers some surprising new information on how to minimize their own role in global warming. Here is Christopher Weber, of Carnegie Mellon University in Pittsburgh, who reported in a May 2008 paper in Environmental Science & Technology.

What you eat can have a very big impact on climate change, mostly because agriculture is a very greenhouse gas intensive production process, as well as all the processing that goes into making food, all the transportation that goes into delivering the food, all of that uses a lot of energy. You combine all that stuff together and agriculture actually accounts for a fairly significant chunk of global greenhouse gas emissions, something on the order of 25 to 30 percent, depending on how you measure it.

Weber reported that substituting chicken, fish, or vegetables for red meat just once a week could help fight climate change. Red meat is much more greenhouse-gas-intensive than chicken, fish, or vegetables.

Red meat, and specifically beef cattle, is about 150 percent more greenhouse gas intensive than chicken or fish is. And there’s a series of reasons for this, the first of which being that beef cattle are not nearly as efficient as chickens at converting grain calories into animal calories. It takes about eight calories to make a calorie of beef, whereas it only takes two to make a calorie of chicken. The second factor is that beef cattle belong to a class of animals called ruminants that can have multiple stomachs, of course, and they release methane from their natural digestion of food and methane is a very potent greenhouse gas. The third is that they produce a lot of manure and the way that manure is typically managed on large-scale farms ends up releasing even more methane and nitrous oxide, which are very potent greenhouse gases.

Weber says some dairy products also are climate change culprits. Cheese production, for instance means more greenhouse gases than chicken.

Conclusion

Meeting the challenge of global warming requires the one-small-step insights, like Dr. Weber’s research on food that consumers themselves can use right now. It takes the stop-gap measures like using switchgrass and stranded natural gas. Ultimately, however, it will take the revolutionary changes like those that DOE’s Dr. Orbach suggested. Please join us here at the American Chemical Society for that next chapter in this ongoing saga of chemistry for life. We’ll take a futuristic look at definitive solutions to this great scientific challenge of the 21st Century. Today’s podcast was written by Marvin Coyner and Michael Woods. Our editor is Michael Woods. I’m Adam Dylewski in Washington.

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